Pressure control valve and method for making a pressure control valve

ABSTRACT

A pressure control valve for an automatic transmission of a motor vehicle includes a valve unit ( 10 ) extruded from plastic, which is disposed coaxially to an actuator unit and serves for control of a fluid flow between a supply port ( 18 ) and a consumer port ( 16 ) and in which fluid channels ( 24, 26 ) and a valve chamber ( 30 ) are formed, in which a valve closing member is arranged. The fluid channels ( 24, 26 ) and the valve chamber ( 30 ) are formed on an injection-molded preform ( 22 ), which is injected into a flange ( 12 ).

BACKGROUND OF THE INVENTION

The present invention relates to a pressure control valve as well as amethod for making a pressure control valve.

Such a pressure control valve is known in practice, and in particular,is designed for use with a hydraulic servo circuit of an automatictransmission of a motor vehicle, whereby, by means of the pressurecontrol valve, the pressure is adjusted in a servo circuit. Via thefluid pressure, a slide valve or the like can be actuated, which servesfor activating a coupling or switching operation. This type of knownpressure control valve includes a valve unit extruded from plastic, inwhich hydraulic channels are formed. A fluid flow flowing between thehydraulic channels can be controlled by means of a valve closing member.

The valve closing member cooperates with a piston or slide valve, whichcan be actuated by means of an actuator unit arranged coaxially to thevalve unit. The actuator unit is formed generally as an electromagneticactuator unit, which includes a magnetic coil, a magnetic core, or polecore, as well as an armature, which cooperates with the piston or slidevalve for actuation of the valve closing member. The valve unit, whichis formed as a type of flange, is extruded onto the magnetic core of theactuator unit. The valve unit of the known pressure control valveincludes an inner hydraulic area in which the hydraulic channels areformed. On the inner hydraulic area, a so-called filter cap is attached,which serves as a sealing element and is sealed by means of an adhesiveconnection.

Manufacturing the adhesive connection, however, is technicallyexpensive. In addition, the adhesive connection has the disadvantagethat with dramatic temperature fluctuations in temperature, a sufficientsealability cannot be achieved.

In addition, it is known to make a valve part of a pressure controlvalve of the above-described type from multiple injection-molded parts,which are connected to one another with an ultra-welding method or alsoby a laser welding method.

Also, these types of sealing methods are expensive, however, and do notpermit an adequate sealability under all conditions of use.

SUMMARY OF THE INVENTION

The pressure regulating valve of the present invention, in which thefluid channels and the valve chambers are formed on a preform that isinjected into a flange, has the advantage that all areas required forpressure control are formed on the preform and no sealing points betweenthe preform representing the inner hydraulic region and the outer regionof the flange, representing the outer hydraulic region of the valvepart, are available, since by the extrusion coating of the preform, ahermetic seal between the preform and the flange can be obtained.

Advantageously, also no further sealing method is required, such as, forexample, an ultra-welding method, a laser-welding method, or an adheringmethod, in order to obtain the required sealability between the innerand outer hydraulic regions.

The pressure control valve of the present invention can operate as apressure control with a decreasing flow-force characteristic line, aswell as a pressure control with an increasing flow-force characteristicline. The actuator unit can be an electromagnetic actuator unit, whichcommonly is formed with a coil, a magnetic core, and an armature. Theflange can be extruded onto the magnetic core.

As already noted, the preform of the pressure valve of the presentinvention represents the inner hydraulic region of the pressure controlvalve. It includes the fluid channels, via which the control of thefluid flow between the supply port and the consumer port takes place.The flange surrounding the preform represents the outer hydraulic regionof the valve part and includes the connections or connecting channels toat least one pressure source, which, for example, is a hydrauliccylinder, and to a consumer, such as a slide valve for actuation of aswitching element of an automatic transmission.

A pressure control valve used in an automatic transmission generally hasa return port, which is connected with a tank for hydraulic oil, wherebya fluid flow flowing to the return port can be controlled by means of aclosure element, which cooperates with a seating plate and is secured toa piston or slide valve for actuation of the valve closing member. Theseating plate, typically made from metal, can be a component of thepreform and upon manufacture of the preform, represents an insert part,which is oriented at a right angle to the longitudinal axis of the valveunit.

With one advantageous embodiment of the pressure control valve of thepresent invention, the preform has at least one, preferably two planesof symmetry arranged at a right angle to one another and parallel to thelongitudinal axis of the pressure control valve. In this regard, thepreform, after extrusion coating with the flange; has a minimumdeformation tendency, which in contrast to an asymmetrical form of theinner hydraulic region, leads to better hydraulic performance of theentire pressure control valve.

The actuation of the valve closing member takes place preferably bymeans of a slide valve, which penetrates through the preform at leastpartially. The stroke of the slide valve can be adjusted by means of theactuator unit.

The valve closing member preferably is formed as a sphere, so that thepressure regulating valve represents a so-called LMK (leakage minimizedby sphere (“Kugel”)) pressure control, with which no leakage occurs inthe normal or idle position of the sphere, that is, upon contact of thesphere on its valve seat. Thus, no energy loss occurs by means ofpossible flowing fluid or hydraulic oil.

The invention also relates to a method for making a pressure controlvalve with a valve unit extruded from plastic, which serves for controlof a fluid flow between a supply port and a consumer port and in whichfluid channels are formed.

For permitting a high stability of the pressure control valve and toobtain a high sealability, first an injection-molded preform is madewith the method of the present invention, on which the fluid channelsare formed. Subsequently, the preform is extrusion-coated with a flange,on which the consumer port and the supply port are formed.

The sealability of the valve part is achieved, therefore, according to amethod, which equals a so-called 2K (two Components)-extrusion-coatingmethod. The hermetic sealing of the preform representing the hydraulicregion takes place by means of the superficial fusing and welding of theedge layer of the preform upon extrusion-coating with the flange. Theplastic of the preform can be identical with the plastic of the flange.It is also contemplated, however, that the two plastics are different,for example, such as in their glass fiber content.

A particularly high sealability between the preform and the flange isachieved when the preform is removed from the mold at a temperature of120° C. and is extrusion-coated with the flange at this temperature.

The manufacturing of the pressure control valve of the present inventiontakes place preferably in an extrusion die, which has a first moldcavity for injection of the preform, as well as a second mold cavity forextrusion of the preform with the flange. The conversion of the preformfrom the first into the second mold cavity takes place, then, by meansof a planetary gear, so that the preform is rotated upon conversion 90°relative to the juncture plane of the extrusion die. In this manner, acorrect orientation of the ports of the flange to the fluid channels ofthe preform is ensured.

Upon extrusion-coating of the preform, the openings of the fluidchannels and the valve chamber are sealed, which takes place by means ofdie pushing devices. In this manner, the mouths of the channel,respectively, are sealed with a slide tongue, while the valve chamber issealed with two slide tongues.

Before the extrusion-coating of the preform with the flange, the valveclosing member can be inserted in the preferably blind-hole type valvechamber of the preform.

Further advantages and advantageous forms of the subject matter of thepresent invention can be derived from the description, the drawings, andthe patent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a longitudinal section through a valve unit of a pressurecontrol valve of the present invention;

FIG. 2 shows a second longitudinal section through the valve unit ofFIG. 1, whereby the sectional-plane is offset at a longitudinal axis of90° to the sectional plane selected in FIG. 1;

FIG. 3 shows a perspective representation of the valve unit of FIGS. 1and 2; and

FIG. 4 shows a perspective representation of a preform of the valve unitaccording to FIGS. 1 through 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIGS. 1 through 3, a valve unit 10 of a pressurecontrol valve is represented, which is used with an automatictransmission of a motor vehicle for hydraulic actuation of a switchingelement, such as a coupler or brake, for example, by performance of agear transmission ratio change.

The valve unit 10 includes a flange 12 extruded from plastic forsecuring and hydraulic adaptation of the pressure control valve to acorresponding component of the automatic transmission.

The flange 12 is extruded onto a magnetic core 14, which is associatedwith an actuator unit (not shown) of the pressure control valve. Theactuator unit can be formed in a common manner and therefore includes acoil, an armature, a piston or slide valve, as well as the magnetic coreor pole core 14 cooperating with the armature.

The flange 12 forming the outer hydraulic region of the valve unit 10includes a consumer port 16, a supply port 18, as well as a return port20. The supply port 18 is connected with a pressure source or a pressuretransducer, for example, with a hydraulic pump, at which point a servocircuit for actuating, for example, a slide valve of the coupler of theautomatic transmission is provided. The valve unit 10 is connected withthis slide valve via the consumer port 16.

In addition, the valve unit 10 is connected via the return port 20 witha tank (not shown) for hydraulic oil, so that the hydraulic oilterminating in the return port 20 is returned into the hydraulic circuitof the automatic transmission.

A bushing-type preform 22 is injected into the flange 12. The fluidchannels 24 and 26 forming the inner hydraulic region of the valve unit10, as well as a valve or spherical chamber 28, are formed in thepreform 22.

In the spherical chamber 28, a sphere 30 serving as a valve closingmember is provided, by means of which a fluid flow or oil flow betweenthe supply port 18 and the consumer port 16 connected with the fluidchannel 24 can be controlled. In this connection, the sphere 30cooperates with the piston or slide valve (not shown here), which can beactuated by means of the armature of the actuator unit and penetratesthe valve unit 10 or the preform 22 along a longitudinal axis 32.

The preform 22 includes further a metal plate or seat plate 34 formed asan insertion part, which cooperates with a closure element secured tothe piston (not shown), so that a fluid flow between the fluid channel26 and the return port 20 leading to the tank can be controlled.

The flange 12 and the preform 22 are made from the same plastic, wherebyupon extrusion-coating of the preform 22 with the flange 12, an edgelayer of the preform 22 is superficially fused and thus is welded withthe flange 12. In this manner, a hermetic sealing of the preform 22forming the inner hydraulic region of the valve unit 10 from the outercontour of the flange 12 is achieved.

The preform 22, which is illustrated in a perspective view in FIG. 4,has two planes of symmetry oriented at a right angle to one another,which are also oriented parallel to the longitudinal axis 32 of thevalve unit 10.

The manufacture of the valve unit 10 with the pole core 14 of thepressure control valve according to the present invention takes place,such that, first, the injection-molded preform 12 shown in FIG. 4 isprepared in a first mold cavity of a extrusion die. After hardening, thepreform is removed from the mold at a temperature of approximately 120°C. and by means of a planetary drive together with the magnetic core 14,is transferred into a second mold cavity of the extrusion die.

Thereupon, the sphere 30 is inserted into the blind-hole-type valvechamber 28, and the transversely arranged openings or mouths of thefluid channels 24 shown in FIG. 2 are sealed by means of a cover plateof a slide valve. The sealing of the valve chamber 28 takes place bymeans of two slider valve cover plates.

Subsequently, the preform 22 and the magnetic core 14 areextrusion-coated with the flange 12, so that the component shown in FIG.3 comprises the valve part 10 and the magnetic core 14. This componentis connected with an electromagnetic component of the above-describedtype.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described herein as apressure control valve and a method for making a pressure control valve,it is not intended to be limited to the details shown, since variousmodifications and structural changes may be made without departing inany way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

1-5. (canceled)
 6. Method for manufacturing a pressure control valvewith a valve unit (10) extruded from plastic and which serves forcontrolling a fluid flow between a supply port (18) and a consumer port(16), and wherein fluid channels (24, 26) and a valve chamber (28) areformed in the valve unit (10), comprising the following steps:manufacturing an injection molded preform (22), wherein the fluidchannels (24, 26) and the valve chamber (28) are formed on the preform(22); and extrusion-coating the preform (22) with a flange (12), whereinthe consumer port (16) and the supply port (18) are formed on the flange(12), and the flange (12) represents an outer hydraulic region of thevalve unit (10).
 7. The method according to claim 6, wherein beforeextrusion-coating of the preform (22) with the flange (12), a valveclosing member (30) is inserted into the valve chamber (28) of thepreform (22).
 8. The method according to claim 6, wherein openings ormouths of the fluid channels (24) and the valve chamber (28) of thepreform (22) are sealed before extrusion-coating with the flange (12).